By Patricia Daukantas

On August 25, 1609, Galileo Galilei showed off his new astronomical telescope to Venetian merchants and lawmakers, so the International Year of Astronomy 2009 collaborators (along with Google) are celebrating the 400^th anniversary of the telescope today.

As noted in this blog earlier this year, 2009 has been filled with exciting outreach projects to get the public involved in all aspects of skywatching. The Franklin Institute of Philadelphia (U.S.A.) is in the final weeks of displaying one of Galileo’s original telescopes. The International Year of Astronomy even has its own hit song in Japan.

OPN’s March 2009 feature article on cutting-edge amateur astronomy mentioned a worldwide observing campaign to study the mysterious binary star known as Epsilon Aurigae. Two astronomers, amateur Jeff Hopkins and professional Robert Stencel, want to get as much data as possible during the star system’s eclipse, which happens only every 27.1 years. This month, Stencel and collaborators have launched a new Web site, Citizen Sky, which provides all the tutorials and guidelines to help members of the public collect scientifically useful observations of the variable star – even without a telescope or binoculars.

In honor of today’s anniversary, the Guardian (U.K.) science blog suggests, “Let’s hear it for the inventors and the toolmakers.” Indeed.

2009-08 August

By Patricia Daukantas

For most of a decade, researchers have been pursuing organic LEDs (OLEDs) as a useful material for flexible displays, solar panels and even data storage. Now, a group based in Illinois (U.S.A.) says that inorganic LEDs (ILEDs) offer possibilities for ultrathin lighting and display systems that are brighter than their organic cousins.

Writing in last Friday’s Science, John A. Rogers of the University of Illinois at Urbana-Champaign (UIUC) and his colleagues described these thin LEDs, which are constructed from epitaxial semiconductor layers that can be printed onto glass, plastic or rubber substrates.

Existing inorganic LEDs are much thicker than organic diodes, and hence more expensive. An accompanying ScienceNOW article describes the Illinois team’s bulk-manufacturing process, which involves creating the diodes on a temporary layer, then depositing them en masse onto the permanent substrate for integration with conductors and insulators.

Besides UIUC, Rogers’ co-workers are affiliated with Northwestern University (Illinois, U.S.A.), Semprius (North Carolina, U.S.A.), Singapore’s Institute of High Performance Computing and Tsinghua University (China).

2009-08 August

By Patricia Daukantas

Scientists associated with the Laser Interferometer Gravitational-Wave Observatory (LIGO) and a separate project called Virgo have refined the upper limit to the background residue of gravity waves that could have been generated billions of years ago in the wake of the Big Bang.

It’s important to note that nobody has actually found gravity waves yet. Researchers have been looking for the “stochastic background” of gravity waves left over from the first few seconds of the existence of the universe. If these waves exist, they could offer a glimpse of physical processes that took place when the very young universe was still opaque to electromagnetic radiation. The non-detection (so far) places constraints on cosmological models and on string theory. LIGO and Virgo researchers reported their finding in the August 20 issue of Nature.

The LIGO project has been featured in plenary talks at a couple of OSA conferences. At CLEO/QELS 2008, David Reitze of the University of Florida (U.S.A.) recounted that Albert Einstein predicted gravity waves in 1916, only to change his mind two decades later. (The audio track and slides from his talk are still available online.) At Frontiers in Optics 2005, OSA’s 89^th annual meeting, LIGO deputy director Stan Whitcomb described how the observatory’s Michelson interferometers could measure length changes no bigger than 10^–18 m.

Likewise, the Italian-French Virgo interferometer is an incredibly sensitive instrument using ultrastable lasers and the most reflective mirror ever built. Both LIGO and Virgo teams are working on second-generation interferometers at least an order of magnitude more sensitive than the current versions.

2009-08 August

By Patricia Daukantas

Optical tweezers with force-feedback, nanoscale lasers and cloud-level wind measurements from ground level are among the many topics featured in OSA’s peer-reviewed journals over the last few months.

A collaboration of scientists based in France, Scotland and England devised the low-cost optical tweezers, which appeared in the June 8 issue of Optics Express. The combination of a high-speed video camera and an inexpensive haptic interface gives the tweezers’ operator a “feel” for the two-dimensional forces being exerted on a 5-µm-diameter bead in a laser trap. According to a recent Laser Focus World article, the researchers will try to expand the force-feedback into the third dimension. The original OE article, which also appears in the Virtual Journal for Biomedical Optics, comes with a couple of QuickTime movie files showing the forces on the bead as it moves around.

Also writing in Optics Express, a group from Arizona State University (U.S.A.) and Technical University of Eindhoven (the Netherlands) reported lasing in tiny, semiconductor-filled metal-insulator-metal waveguides. The team used an innovative combination of semiconductors and metals, such as gold and silver, to get around the so-called diffraction limit.

Two scientists from the University of Hawaii (U.S.A.) have used ground-based stereo cameras to derive wind speeds in the upper (cloud) layers of the troposphere. According to their article in the August 15^th Optics Letters, the pair captured cloud features on successive images taken with specially calibrated cameras set about 150 m apart at the Mauna Loa Observatory. From these images they derived wind speed and direction with errors of generally less than 10 percent for clouds 2 km in altitude.

2009-08 August